Direct current motor with transistorized power supply



Sept. 20, 1966 MQCZALA 3,274,471

DIRECT CURRENT MOTOR WITH TRANSISTORIZED POWER SUPPLY Filed Sept. 1,1964 2 Sheets-Sheet 1 1 2 3 4 l 2/ 22 23 24 2 I2 13 /4 {6 5 .4 3/T 32T I33-1- I 342T /5 /5 35 Sept. 20, 1966 H. MOCZALA 3,274,471

DIRECT CURRENT MOTOR WITH TRANSISTORIZED POWER SUPPLY Filed Sept. 1,1964 2 Sheets-Sheet 2 .70 v2 far' -rroRNEm United States Patent3,274,471 DIRECT CURRENT MOTOR WITH TRANSISTOR- IZED POWER SUPPLY HelmutMoczala, Berlin-Grunewalrl, Germany, assignor to LicentiaPatent-Verwaltungs-G.m.b.H., Frankfurt am Main, Germany Filed Sept. 1,1964, Ser. No. 393,572 Claims priority, application Germany, Sept. 6,1963, L 45,797 8 Claims. (Cl. 318-138) The present invention relates toa direct current (DC) motor whose armature windings are connected to atransistorized power supply.

A motor control arrangement of thies type is shown in copendingapplication Serial No. 380,266, filed July 6, 1964, by Julian Hartmannand Helmut Moczala, for Direct Current Motor with Transistorized PowerSupply, wherein the rotational speed of a DC. motor is regulated in thatthe transistors feeding the armature windings are controlled by acontrol circuit as a function of the instantaneous angular position ofthe rotor relative to the stator. The control circuit is constituted bya feedback circuit which consists of control windings and of a controltransistor, this control circuit inducing the control windings which inturn control the armature transistors. According to the arrangementshown in the mentioned application, a so-called tachometer voltage,i.e., a voltage which is a function of the rotational speed of themotor, is generated, which tachometer voltage is applied to the controlcircuit of the motor. When a predetermined, socalled nominal speed isreached, the tachometer voltage renders the control circuit ineffective,thereby to interrupt the flow of current through the armature. Themagnetic inductor for the tachometer voltage is constituted by themagnetic cylindrical rotor of the motor. The windings in which thetachometer voltage is induced lie in the same slots as the actualoperating windings of the motor.

For a better understanding of the above-described arrangement disclosed,in the prior application, which is believed essential in order to obtaina fuller appreciation of the present invention, to be described indetail below, reference is made to FIGURES l to 3 of the accompanyingdrawings, in which FIGURE 1 is a perspective diagrammatic representationof a motor according to the prior application and shows certain ones ofthe electromechanical components, FIGURE 2 is a circuit diagram of oneembodiment of the motor control arrangement according to the priorapplication, and FIGURE 3 is a graph of the timed relationship of avoltage eifective in the motor control circuit of FIGURES 1 and 2.

FIGURES 1 and 2 show a rotor 17' mounted on a shaft 16, this rotorbeing, for the sake of simplicity, represented as a rotating,cylindrical magnet whose polarity is shown at N and S. The stationaryarmature windings, being the operating windings, are indicated at 1, 2,3, 4. These windings are connected to transistors 11, 12, 13, 14 (FIGURE2) which, in accordance with the particular angular position of themagnetic rotor, cause D.C. pulses to flow through the windings, incyclical sequence, such that the magnet rotor is, as in a rotatingfield, continuously subjected to an electromagnetic pull or torque,thereby to start the motor and to maintain the rotor in rotation so longas a battery is switched in by closing of a switch 6.

The cyclic sequence of the electronic control of the armaturetransistors, which function as controlled switching transistors, isbrought about by the motor itself. Mounted on the shaft 16 for rotationtherewith is a carrier 18 carrying a block 19, made of high-frequencyiron or ferrite and having the shape of an amcuate segment. The purposeof this segment 19 is to conduct the magnetic 3,274,471 Patented Sept.20, 1966 flux of .a high-frequency oscillator (this being the feedback),consisting of the windings 35 and 36 which are wound on a core 37, 38,the control transistor 15, and the capacitors 16 and 17, cyclically fromcore 38 to the cores of the control windings 31, 32, 33-, 3 4. Thehigh-frequency voltages induced in these control windings 31, 32, 33,34, are rectified by means of respective diodes 21, 22, 23, 24, and areapplied, as control voltages, to the bases of the armature transistors11, 12 13, 14. The emittercollector path of each transistor thus remainsconductive as long as a control voltage is applied to it, i.e., so longas there is a magnetic flux passing through the respective control coil.The oscillator itself, of course, remains excited so long as the battery5 is connected to the circuit by means of the switch 6.

The transistor-fed DC. motor could, theoretically, continuously increaseits rotational speed until its counter electromotive force is induced inthe armature windings, if no provision were made for maintaining a givenpredetermined rotational speed. According to the invention disclosed inthe prior application, the rotational speed is limited by turning oifthe oscillator and hence the high-frequency control, this being done byapplying to the base of the oscillator transistor the above-mentionedtachometer voltage which is proportional to the increasing rotationalspeed. Consequently, when there is no longer any regulation, thearmature windings 1, 2, 3, 4, will no longer be fed with any currentpulses, as a result of which the motor reduces its speed. But as therotational speed drops, the tachometer voltage, i.e., the voltage whichis proportional to the rotational speed of the motor, drops below theblocking voltage of the oscillator transistor, and this will, in amanner of speaking, again turn on the oscillator and the high-frequencycontrol becomes effective once more. The motor therefore again has adriving pulse applied to it. This entire process is repeated, withinnarrow limits, of course, so that the motor will run at what is, for allpractical purposes, a constant speed.

The basic components by means of which the rotational speed of the motoris regulated, together with their function, will be explained inconjunction with FIGURES 1 and 2. The cylindrical magnetic rotor 17serves as the magnetic inductor of the tachometer generator whichdelivers the tachometer voltage, the same being induced in tachometerwindings 26, 27, 28, 29, which lie in the same slots as do the workingwindings 1, 2, 3, 4.- The tachometer windings are connected, viarespective rectifier diodes 46, 4 7, 48, 49, and a control potentiometer51 to the socalled tachometer circuit such that the rectified voltagetaken off potentiometer 51 is applied via a Zener diode 50 to theemitter-base path of the oscillator transistor 15, whereat it acts as ablocking voltage. The Zener diode maintains this blocking voltageconstant at a value which is precisely of such amplitude as to stop theoscillation.

The graph of FIGURE 3 shows the blocking voltage V which is limited bythe Zener diode 50, this being a rectified sinusoidal voltage of asingle exciter path of the tachometer generator. The rectifiedtachometer generator voltage can, for example, be so reduced by thepotentiometer that the motor again has to increase its speed until thetachometer generator voltage increases and reaches the blocking voltage,whereupon the motor will be driven at the new, increased rotationalspeed. If this voltage is increased by the potentiometer, the rotationalspeed of the motor is reduced. In this way, the nominal r.p.m., i.e.,the predetermined rotational speed at which the motor is to run, may beadjusted, within a wide range, by the potentiometer 51.

It is the primary object of the present invention to provide a controlarrangement of the above type which is an improvement of the arrangementdisclosed in the prior application, particularly to provide anarrangement in which the separate tachometer windings can be dispensedwith.

Accordingly, the present invention resides in an arrangement of the samegeneral type as described above, there being, however, no separatetachometer windings. Instead, the tachometer potential is derived fromthe armature windings themselves while the same are blocked from thepower supply by the respective armature transistors.

Additional objects and advantages of the present invention will becomeapparent upon consideration of the following description when taken inconjunction with the accompanying drawings in which:

FIGURE 1 is a perspective diagrammatic view of a motor according to theinvention disclosed in the abovementioned application Serial No.380,266.

FIGURE 2 is a circuit diagram of the motor control arrangement accordingto the invention of application Serial No. 380,266.

FIGURE 3 is a graph showing the time relationship of a voltage appearingin the circuit of FIGURE 2. 4

FIGURE 4 is a circuit diagram of one embodiment of a motor controlarrangement according to the present invention.

FIGURE 5 is a graph showing the timed relationship of the voltageeffective in the motor control circuit of FIGURE 4.

FIGURE 6 is a circuit diagram of part of another embodiment of a motorcontrol arrangement according to the present invention.

FIGURE 7 is a circuit diagram of a part of yet another embodiment of amotor control arrangement according to the present invention.

FIGURE 8 is a circuit diagram of still a further embodiment of a motorcontrol arrangement according to the present invention.

Referring once again to the drawings and now to FIG- URE 4 thereof, inwhich the same reference numerals are used to represent componentsanalogous to those described above, the stationary armature windings,i.e., the actual working windings 61, 62, 63, are controlled by therespective switching transistors 11, 12, 13 such that, so long as thebattery 5 is connected in circuit by closing of the switch 6, DC. pulseswill be made to flow cyclically through the windings, depending on theinstantaneous angular position of the rotor with respect to the stator,so as to subject the rotor to an electromagnetic torque, in the mannerof a rotating electric field. As before, the segment 19 acts to send themagnetic flux of the high-frequency oscillator cyclically through thecontrol windings 31, 32, 33. The high-frequency voltages induced in thecontrol windings are rectified by the diodes 21, 22, 23 and are applied,as control voltages, to the emitter-base paths of the armaturetransistors. Consequently, the emitter-collector path of each armaturetransistor remains conductive so long as a control voltage is applied,i.e., so long as there is a magnetic fiux through the correspondingcontrol winding, the oscillator remaining excited as long as the battery5 is switched in.

As before, the motor, which would increase its rotational speed untilits counter electromotive force is induced in the armature windings, isregulated to a predetermined speed by the application of a tachometervoltage. The same is, in the arrangement shown in FIG- URES 1 and 2,representing the invention disclosed in the prior application, derivedfrom the separate windings 26, 27, 28, 29. According to the presentinvention, however, the tachometer voltage for speed-regulating themotor is derived from the very same armature windings which produce therotary field that drives the motor. To this end, one terminal of each ofthe armature windings 61, 62, 63, is connected to the positive terminalof the battery 5, while the other terminal of each armature Winding isconnected to the negative terminal of the battery via theemitter-collector path of the corresponding switching transistor 11, 12,13. Furthermore, the armature windings 61, 62, 63, are connected, viarespective rectifier diodes 71, 72, 73, a capacitor 86 and theregulating potentiometer 51 to the so-called tachometer circuit. Thepotential taken off the tap of the potentiometer 51 is applied via theZener diode 50 to the emitter base path of the control transistor 15,there to act as a blocking voltage. The Zener diode holds the blockingvoltages constant and interrupts the oscillator voltage.

In this way, the armature windings 61, 62, 63, serve a double purpose,namely, to produce the rotary field which drives the rotor and to yieldthe tachometer voltage. This is made possible by the fact that thearmature windings, in contradistinction to armature windings ofconventional DC. motors provided with brushes, have a voltage connectedacross them by the respective switching transistors only throughout theworking half-wave of the operating cycle, as shown in FIGURE 5 at 61,62', 63, the amplitude of the working half-wave being derived from theelectromotive force (E.M.F.) which is enlarged by V and, in accordancewith this amount, is equal to the voltage V of the battery 5. As aresult, the armature windings are available during the other half of theoperating cycle, which may be called the measuring half-wave as opposedto the above-mentioned working half-wave; this is shown at 61", 62",63", during which measuring half-wave the may be measured, as depictedin FIGURE 5.

The three armature windings 61, 62, 63, forming part of the arrangementdescribed above are, in practice, oriented radially with respect to thecenter of the rotor and are angularly displaced from each other. Thewindings are so designed that the measuring half-wave 61", 62", 63", aretrapezoidal and provide a constant measuring voltage which is used, inthe manner described above, as the tachometer voltage for the purpose ofregulating the speed of the motor.

It will be seen from the above that the present invention resides in adirect current motor having a stator and a rotor, a plurality ofarmature windings, a power supply, a plurality of armature transistorsconnecting the power supply to the respective armature windings, controlcircuit means connected to the armature transistors for controlling thesame in dependence upon the relative angular position between the statorand rotor, which control circuit means include an oscillatory circuitincorporating a control transistor, and speed regulating means connectedto the control transistor for applying thereto a potentiometerpotential, dependent on the rotational speed of the motor, which rendersthe control circuit means ineffective at a given predeterminedrotational speed. The speed regulating means themselves incorporatemeans connected to the armature windings for deriving the tachometervoltage from the armature windings throughout respective parts of eachrevolution of the motor, and means for rendering the armaturetransistors non-conductive during the respective parts of eachrevolution, thereby blocking the respective armature windings from thepower supply during the respective parts of each revolution.

FIGURE 6 shows an arrangement by means of which the motor may beregulated to run at more than one predetermined spec-d. To this end,each armature windingtor purposes of simplicity, only one armaturewinding 83 is illustrated in FIGURE 6-is subdivided into a plurality ofparts, corresponding in number to the number of speeds to which themotor is to be regulated. Thus, the circuit of FIGURE 6 shows theWinding 83 as having a plurality of taps each of which may be connected,by means of a selector switch 84, to the positive terminal of thebattery 5.

The circuit of FIGURE 7 is basically similar to that of FIGURE 6, anddiffers therefrom only in that each of the several armature windingsofwhich only winding 83a is illustrated in FIGURE 7-is permanentlyconnected to the positive terminal of the battery 5 but has a pluralityof taps each of which is connectible, by means of a switch 85, to theemitter collector circuit of the armature transistor 13.

FIGURE 8 shows a circuit in accordance with the present inventionwherein the motor may be regulated to run at either of two speeds whichare in the ratio of 1:2 to each other. To this end, each of the armaturewindings is subdivided into two equal parts 64, 65; 66, 67; 68, 69. Eachtwo-part winding has associated with it a double-pole switch, 87, 88,89, so that the two parts of each winding can be connected into thecircuit either serially (position I) or parallelly (position 11). Thethree switches 87, 88, 89 are ganged by means of a linkage 90. In thisway, the motor may be made to run at either of its two speeds whilemaintaining the same eificiency, this being due to the fact that in eachof its running positions the motor makes use of the whole of each of itswindings.

It will be appreciated that the present invention constitutes animprovement over the arrangement shown in the mentioned priorapplication in that, the separate tachometer windings being dispensedwith, only the operating windings need to be accommodated within thestator slots, as a result of which these armature windings can be madeof heavier wire than if space had to be provided for separate tachometerwindings. This, in turn, makes it possible to provide a motor having ahigher efficiency. Furthermore, a conventional D.C. motor whose armaturewindings are fed by a transistorized circuit but not equipped with anyspeed regulating means can, by following the present invention, beconverted for use as a speed-controlled motor.

It will be understood that the above description of the presentinvention is susceptible to various modifications, changes andadaptations, and the same are intended to be comprehended within themeaning and range of equivalents of the appended claims.

What is claimed is:

1. In a DC. motor having a stator and a rotor, the combination whichcomprises: three armature windings displaced 120 relative to each other;a power supply; a plurality of armature transistors connecting saidpower supply to respective ones of said windings; control cirouit meansconnected to said armature transistors for controlling the same independence on the relative angular position between the stator androtor, said control circuit means including an oscillatory circuitincorporating a control transistor; and speed regulating means connectedto said control transistor for applying thereto a tachometer potential,dependent on the rotational speed of the motor, which renders saidcontrol circuit means ineffective at a given predetermined rotationalspeed, said speed regulating means incorparating means connected to saidarmature windings for deriving said tachometer voltage from saidarmature windings throughout respective par-ts of each revolution of themotor, and means connected to said armature transistors for renderingthe same non-conductive during said respective parts of each revolution,thereby blocking the respective armature windings from said powersup-ply during said respective parts of each revolution.

2. The combination defined in claim 5 wherein said power supply haspositive and negative terminals, and wherein each of said armaturewindings is connected directly to said positive terminal of said powersupply and is connected to said negative terminal of said power supplyvia the emitter-collector path of the respective armature transistor.

3. The combination defined in claim 2 further comprising means forrendering each of said armature transistors non-conductive during arespective part of each revolution of the motor and including aplurality of control windings each connected between the emitter andbase of a respective armature transistor.

4. The combination defined in claim 2 further comprising a plurality ofrectifiers each connected between a respective one of said armaturewindings and said control transistor, and a capacitor connected inparallel with all of the paths defined by said rectifiers and saidarmature windings.

5. In a DC. motor having a stator and a rotor, armature windings, apower supply, armature transistors connecting the power supply to thearmature windings, a control circuit connected to the armaturetransistors for controlling the same in dependence upon the relativeangular position between the stator and rotor, the control circuitincluding an oscillatory circuit incorporating a control transistor, andspeed regulating means connected to the control circuit for applyingthereto a tachometer potential, dependent on the rotational speed of themotor, which renders the control circuit ineffective at a givenpredetermined rotational speed, the improvement that said tachometerpotential is derived :from said armature windings while the same areblocked from said power supply by said armature transistors.

6. In a DC. motor having a stator and a rotor, the combination whichcomprises: a plurality of armature windings each subdivided into aplurality of parts; a power supply having positive and negativeterminals, with each of said armature windings being connected directlyto said positive terminal; a plurality of armature transistors eachhaving an emitter-collector path via which a respective one of saidarmature windings is connected to said negative terminal; controlcircuit means connected to said armature transistors for controlling thesame in dependence on the relative angular position between the statorand rotor, said control circuit means including an oscillatory circuitincorporating a control transistor; speed regulating means connected tosaid control transistor for applying thereto a tachometer potential,dependent on the rotational speed of the motor, which renders saidcontrol circuit means ineifective at a given predetermined rotationalspeed, said speed regulating means incorporating means connected to saidarmature windings for deriving said tachometer voltage firom saidarmature windings throughout respective parts of each revolution ofmotor, and means connected to said armature transistors for renderingthe same nonconductive during said respective parts of each revolution,thereby blocking the respective armature windings from each said powersupply during said respective parts of said revolution; and switch meansprovided for connecting any given part of each armature winding to saidpositive terminal of said power supply, thereby to enable the speed ofthe motor to be regulated to any one of a plurality of speeds.

7. In a DC. motor having a stator and a rotor, the combination whichcomprises: a plurality of armature windings each subdivided into aplurality of parts; a power supply having positive and negativeterminals, with each of said armature windings being connected directlyto said positive terminal; a plurality of armature transistors eachhaving an emitter-collector path via which a respective one of saidarmature windings is connected to said negative terminals; controlcircuit means connected to said armature transistors for controlling thesame in dependence on the relative angular position between the statorand rotor, said control circuit means including an oscillatory circuitincorporating a control transistor; speed regulating means connected tosaid control transistor for applying thereto a tachometer potential,dependent on the rotational speed of the motor, which renders saidcontrol circuit means ineffective at a given predetermined rotationalspeed, said speed regulating means incorporating means connected to saidarmature windings for deriving said tachometer voltage from saidarmature windings throughout respective parts of each revolution of themotor, and means connected to said armature transistors for renderingthe same nonconductive during said respective parts of each revolution,thereby blocking the respective armature windings from said power supplyduring said respective parts of said revolution; and switch means forconnecting any given part of each said armature winding to theemitter-collector path of the respective armature transistor and henceto said negative terminal of said power supply, thereby to enable thespeed of the motor to be regulated to any one of a plurality ofdifierent speeds.

8. In a D.C. motor having a stator and a rotor, the combination whichcomprises: a plurality of armature windings each subdivided into twoequal parts; a power supply having positive and negative terminals, witheach of said armature windings being connected directly to said positiveterminal; a plurality of armature transistors each having anemitter-collector path via which a respective one of said armaturewindings is connected to said negative terminal; control circuit meansconnected to said armature transistors for controlling the same independence on the relative angular position between the stator androtor, said controlcircuit means including an oscillatory circuitincorporating a control transistor; speed regulating means connected tosaid control transistor for applying thereto a tachometer potential,dependent on the rotational speed of the motor, which renders saidcontrol circuit means ineffective at a given predetermined rotationalspeed, said speed regulating means incorporating means connected to saidarmature windings for deriving said tachometer voltage from saidarmature windings throughout respective parts of each revolution ofmotor, and means connected to said armature transistors for renderingthe same n-onconductive during said respective parts of each revolution,thereby blocking the respective armature windings from each said powersupply during said respective parts of said revolution; and switch meansfor selectively connecting the two parts of each winding in series or inparallel, thereby to enable the speed of the motor to be regulated toeither of two speeds which bear a 1:2 relationship to each other.

References Cited by the Examiner UNITED STATES PATENTS 2,814,769 11/1957Williams 318138 X 3,124,733 3/1964 Andrews 318--254 X ORIS L. RADER,Primary Examiner.

S. GORDON, G. SIMMONS, Assistant Examiners.

5. IN A D.C. MOTOR HAVING A STATOR AND A ROTOR, ARMATURE WINDINGS, APOWER SUPPLY, ARMATURE TRANSISTORS CONNECTING THE POWER SUPPLY TO THEARMATURE WINDINGS, A CONTROL CIRCUIT CONNECTED TO THE ARMATURETRANSISTORS FOR CONTROLLING THE SAME IN DEPENDENCE UPON THE RELATIVEANGULAR POSITION BETWEEN THE STATOR AND ROTOR, THE CONTROL CIRCUITINCLUDING AN OSCILLATORY CIRCUIT INCORPORTATING A CONTROL TRANSISTOR,AND SPEED REGULATING MEANS CONNECTED TO THE CONTROL CIRCUIT FOR APPLYINGTHERETO A TACHOMETER POTENTIAL, DEPENDENT ON THE ROTATIONAL SPEED OF THEMOTOR WHICH RENDERS THE CONTROL CIRCUIT INEFFECTIVE AT A GIVENPREDETERMINED ROTATIONAL SPEED, THE IMPROVEMENT THAT SAID TACHOMETERPOTENTIAL IS DERIVED FROM SAID ARMATURE WINDINGS WHILE THE SAME AREBLOCKED FROM SAID POWER SUPPLY BY SAID ARMATURE TRANSISTORS.